Kiệt Gia 908 Questions 2k Answers 0 Best Answers 27 Points View Profile0 Kiệt Gia Asked: Tháng Mười 23, 20202020-10-23T11:30:23+00:00 2020-10-23T11:30:23+00:00In: Môn Toánx^3+3x^2+3x=0 x^3=4x x^3-49x=00x^3+3x^2+3x=0 x^3=4x x^3-49x=0 ShareFacebookRelated Questions Một hình thang có đáy lớn là 52cm ; đáy bé kém đáy lớn 16cm ; chiều cao kém đáy ... Useful news and important articles APROTININ FROM BOVINE LUNG CELL CULTURE купить онлайн2 AnswersOldestVotedRecentHelga 884 Questions 2k Answers 0 Best Answers 19 Points View Profile Helga 2020-10-23T11:31:39+00:00Added an answer on Tháng Mười 23, 2020 at 11:31 sáng Đáp án: $x^3+3x^2+3x=0$$⇔x(x^2+3x+3)=0$$⇔x^2+3x+3=0$$⇔x^2 +2 .x \dfrac{3}{2} + \dfrac{9}{4} + \dfrac{3}{4}=0$$⇔(x+\dfrac{3}{2})^2 +\dfrac{3}{4} > 0 ∀ x$ (loại)$⇔x=0$Vậy $x=0$____________________$x^3=4x$$⇔x^3-4x=0$$⇔x^3-2x^2+2x^2-4x=0$$⇔x^2(x-2)+2x(x-2)=0$$⇔(x-2)(x^2+2x)=0$$⇔x(x+2)(x-2)=0$⇔\(\left[ \begin{array}{l}x=0\\x+2=0\\x-2=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=-2\\x=2\end{array} \right.\) Vậy $\text{x ∈ {0 ; 2 ; -2} }$___________________________$x^3-49x=0$$⇔x^3-7x^2+7x^2-49x=0$$⇔x^2(x-7)+7x(x-7)=0$$⇔(x-7)(x^2+7x)=0$$⇔x(x+7)(x-7)=0$⇔\(\left[ \begin{array}{l}x=0\\x+7=0\\x-7=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=-7\\x=7\end{array} \right.\) Vậy $\text{ x ∈ {0 ; -7 ; 7 } }$0Reply Share ShareShare on FacebookDâu 863 Questions 2k Answers 0 Best Answers 17 Points View Profile Dau 2020-10-23T11:32:22+00:00Added an answer on Tháng Mười 23, 2020 at 11:32 sáng Giải thích các bước giải: `x^3+3x^2+3x=0``=>(x^3+3x^2+3x+1)-1=0``=>(x+1)^3=1``=>x+1=1``=>x=0` `x^3=4x``=>x^3-4x=0``=>x(x^2-4)=0``=>x(x-2)(x+2)=0``=>`\(\left[ \begin{array}{l}x=0\\x-2=0\\x+2=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=2\\x=-2\end{array} \right.\) `x^3-49x=0``=>x(x^2-49)=0``=>x(x-7)(x+7)=0``=>`\(\left[ \begin{array}{l}x=0\\x-7=0\\x+7=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=7\\x=-7\end{array} \right.\)0Reply Share ShareShare on FacebookLeave an answerLeave an answerHủy By answering, you agree to the Terms of Service and Privacy Policy .* Lưu tên của tôi, email, và trang web trong trình duyệt này cho lần bình luận kế tiếp của tôi.
Helga
Đáp án:
$x^3+3x^2+3x=0$
$⇔x(x^2+3x+3)=0$
$⇔x^2+3x+3=0$
$⇔x^2 +2 .x \dfrac{3}{2} + \dfrac{9}{4} + \dfrac{3}{4}=0$
$⇔(x+\dfrac{3}{2})^2 +\dfrac{3}{4} > 0 ∀ x$ (loại)
$⇔x=0$
Vậy $x=0$
____________________
$x^3=4x$
$⇔x^3-4x=0$
$⇔x^3-2x^2+2x^2-4x=0$
$⇔x^2(x-2)+2x(x-2)=0$
$⇔(x-2)(x^2+2x)=0$
$⇔x(x+2)(x-2)=0$
⇔\(\left[ \begin{array}{l}x=0\\x+2=0\\x-2=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-2\\x=2\end{array} \right.\)
Vậy $\text{x ∈ {0 ; 2 ; -2} }$
___________________________
$x^3-49x=0$
$⇔x^3-7x^2+7x^2-49x=0$
$⇔x^2(x-7)+7x(x-7)=0$
$⇔(x-7)(x^2+7x)=0$
$⇔x(x+7)(x-7)=0$
⇔\(\left[ \begin{array}{l}x=0\\x+7=0\\x-7=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-7\\x=7\end{array} \right.\)
Vậy $\text{ x ∈ {0 ; -7 ; 7 } }$
Dâu
Giải thích các bước giải:
`x^3+3x^2+3x=0`
`=>(x^3+3x^2+3x+1)-1=0`
`=>(x+1)^3=1`
`=>x+1=1`
`=>x=0`
`x^3=4x`
`=>x^3-4x=0`
`=>x(x^2-4)=0`
`=>x(x-2)(x+2)=0`
`=>`\(\left[ \begin{array}{l}x=0\\x-2=0\\x+2=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=2\\x=-2\end{array} \right.\)
`x^3-49x=0`
`=>x(x^2-49)=0`
`=>x(x-7)(x+7)=0`
`=>`\(\left[ \begin{array}{l}x=0\\x-7=0\\x+7=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=7\\x=-7\end{array} \right.\)